Bring up the talk bar by pressing T then enter codes as written here:

• eyeofgod: Allows extra level of zoom on lower-level machines
• saladtossed: Choose any mission (enter the code, exit the current mission to the Main Menu, press the CTRL+H+W keys simultaneously, then click on Load and a mission)
• twobyfour: Builds any unit (for example, twobyfour dragoon for a Dragoon Tank-most of the names are logical, but some use a British spelling for "centre," "defence," and so on)
• hermes: Speeds up ordering of units
• donkeys: Anything that shoots missiles now shoots Jeeps instead
• morningafter: Removes the "fog of war" from the entire map.
• gimmiegimmie: Allows you to build everything, even without a Command Center/Command Complex
• unclejohn: God mode (your units can't be destroyed)
• chaching: Adds $10,000 to your resources
• mrmuscle: Upgrades your armor percentage
• bigsofty: Downgrades your enemy's armor percentage
• coffee: Upgrades your speed percentage
• beer: Downgrades your enemy's speed percentage
• shaft: Upgrades your firepower percentage
• shank: Downgrades your enemy's firepower percentage